Phenoxyacetamides for the control of pests



3,166,589 Patented Jan. 19., 1965 3,166,589 'PI-IENOXYACETAMIDES FOR THE CONTRGL F PESTS Sidney B. Richter, Chicago, Ill., assignor to Velsicol Chemical Corporation, Chicago, Ill., a corporation of Illinois No Drawing. Filed Nov. 20,1?62, Ser. No. 239,071

' 9 Claims. (Cl. 260-559) This invention relates to the control of undesirable pests. pro-emergence controlof undesirable plant life, particularly crabgrass.

It has now been found that undesirable plant life can be controlled very effectively 'with the use of chemical compounds which are N-monoalkoxy amides of 2,fl,5- trichlorophenoxy alkyl acids. These new chemical compounds have the structural formula f (l)Zi)-N H Cl wherein X is selected from the group consisting of hydrogen, and substituted and unsubstituted alkyl groups, Y is selected from the group consisting of substituted and unsubstituted alkyl groups, and Z is an unsubstituted alkylene group containing from one to four carbon atoms. In .a preferred embodiment of this invention, Z is as described above, X is selected from the group consisting of hydrogen and unsubstituted alkyl groups containing from one to ten carbon atoms, and Y is an unsubstituted alkyl group containing from one to tencarbon atoms.

The novel alkoxy amides 0f the present invention can be prepared conveniently from'the corresponding acid, which is often commercially available, or can be synthesized by treating the corresponding 2,4,5-trichlorophenol with an alkali metal hydroxide to form the salt, and treating the salt with a bromo-alkyl acid of the formula v Br-Z-COOH wherein Z is as described ab0ve, or a lower alkyl ester of the acid, and then hydrolyzing. Alternatively, free acids, other than 2,4,S-trichlorophenoxy-acetic acids can be prepared from the corresponding 2,4,5-trichlorophenoxyalkyl acid wherein Z has one less CH group attached to the COOH group than in the desired free acid, by reducing the lower acid with lithium aluminum hydride at a low temperature, treating the resulting alcohol with thionyl chloride to obtain the halide, treating the halide with sodium cyanide and then hydrolyzing the product to obtain the free acid.

Examples of the free acids from which the. compounds of the present invention. can be prepared, are:-

2,4,5-trichlor ophenoxy acetic acid, a-(2,4,5-trichlorophenoxy) propionic acid, ,8;(2,4,5-trichlorophenoxy) propionic acid, a-(2,4,5-trichlorophenoxy) -n,-butyric acid, 13-(2,4,5-trichlorophenoxy)-n-butyric acid, 'y-(2,4,5-trichlorophenoxy)-n-butyric acid, a-(2,4,5-trichlorophenoxy)-iso-butyric acid,

a- (2,4,5 -trichlorophenoxy) -n-valeric acid, =y-(2,4,5-trichlorophenoxy)-n-valeric acid, r 6 (2,4,5-trichlorophenoxy) il-Valerie acid, and the like.

The free acid can then be converted to its acid 'chlo- More specifically, this invention relates to the i desired compound ofthe present invention.

ride, which is treated with an alkoxyamine of the formula X .H-N

wherein X and Y are as described above, to give the Suitable amines of the above formula can be prepared, for example, by the reduction of the corresponding oximes as described by Jones and Major, J. Am. Chem. Soc., vol. 52, pp. 669-79 (1930). Exemplary of suitable alkoxy amines useful as a reactant to prepare the N- alkoxy amides of the present invention, are: N-methoxyamine, N-methoxy-N-methylamine, N-ethoxyamine, N- ethoxy-N-methylamine, N-ethoxy N ethylamine, N- methoxy-N-ethylamine, N n propoxyamine, N isopropoxyamine, N-mpropoxy-N-ethylamine, and the like.

More particularly, the free acid is treated with an equimolar or greater quantity of thionyl chloride, preferably in a solvent or diluent, such as benzene. An amount of solvent or diluent approximately equal in volume to the volume of the free acid has been found to be satisfactory. The treatment is performed by heating for several hours, preferably at reflux if a solvent or diluent, such as benzene, or large excess of thionyl chloride is used. The corresponding acyl chloride thus formed can be isolated'from the reaction mixture by means com- -rnon'to the art, such asby distillation of the solvent or diluent and unreacted reactants, leaving the acyl chloride as the residue. i

In the second step, the acyl chloride is reacted with an equimolecular or greater amount of the appropriate N- alkoxyarnine or preferably its hydrochloride, in the presence of a base, such as sodium hydroxide, potassium hydroxide, and potassium carbonate. alent quantity of base, is used when the free amine is utilized as the reactant, and at least twice that amount is used when the amine hydrochloride is used as the reactant. The base is used to release the amine from its hydrochloride, and to neutralize the hydrogen chloride, formed during the reaction. A small amount of water is preferably added to the reaction mixture to form an aqueous solution-of the base to aidin mixing the base into the solution of the amine or amine-hydrochloride reactant.

The reaction is conveniently performed utilizing a solvent is used. 'When potassium carbonate is used as the base,

completion of'the reaction can bereadily detected by the cessation of the release of carbon dioxide gas. The N- alkoxy amide compound of the present invention formed by the above procedurecan be separated from the reaction mixture by means common to the art, such as by filtration from precipitated salts and unreacted amine, drying the filtrate and distilling the filtrate under reduced pressure to remove unreacted reactants and solvent or diluent, ifused, and to recover the desired product as the residue; The N-alkoxy amide compound of the present invention thus obtained can be used for many applications as such, or can be recrystallized from a suitable solvent.

The manner in which the new compounds of this invention can be prepared is illustrated in the following examples. i

EXAMPLE 1 '2,4,S-trichlorophenoxyacetic acid -g.; 0.59 mol) andbenzene (150 ml.) were placed'into a one-liter, threenecked, round-bottom flask fitted with a mechanical stirrer,

At least one equivs3! reflux condenser, and a dropping funnel. The contents of the flask were stirred and thionyl chloride (46 1111.; 0.646 mol) was slowly added to the flask. The contents were heated to reflux, and stirring was continued at reflux for six hours. The reaction mixture was dried over magnesium sulfate, filtered and distilled under reduced pressure to remove benzene and unreacted thionyl chloride. The residue was distilled in vacuo to yield the product 2,4,5-trichlorophenoxyacetyl-chloride, as a clear liquid boiling at 105ll8 C./0.11 mm. Hg pressure, which solidified into a light yellow solid.

EMMPLE 2 Preparation of N-methoxy-N-methyl-2,4,5-

triclzlorophenoxyacetamide N methoxy N rnethylamine hydrochloride (6.6 g.; 0.068 mol), potassium carbonate (10.4 g.; 0.075 mol), benzene (50 ml.) and water (2 ml.) were placed in a 300-ml., three-necked, round-bottom flask, equipped with a mechanical stirrer, reflux condenser, and dropping funnel. The mixture was stirred, and 2,4,5-trichlorophenoxyacetyl chloride (18.6 g.; 0.068 mol) in benzene (50 ml.), prepared in Example 1, was slowly added to the flask. The reaction was exothermic, and the mixture was thereafter stirred at reflux for 6 hours. The reaction mixture was filtered and the solids washed thrice with benzene. The benzene washings were combined with the filtrate, dried over magnesium sulfate, filtered, and the filtrate distilled under reduced pressure to remove benzene and to yield a white solid residue. This residue was 9 recrystallized from heptane to give the product N-methoxy-N-methyl 2,4,5 trichlorophenoxyacetamide melting l21.5123.5 C., and having the following elemental analysis:

Calculated for CmHmClsNOgI Methoxyamine-hydrochloride (5.9 g.; 0.070 mol), potassium carbonate (10.6 g.; 0.077 mol), benzene (50 ml.) and water (10 ml.) were placed in a 300 ml. three-necked, round-bottom flask fitted with a mechanical stirrer, reflux condenser and dropping funnel. The mixture was stirred, and 2,4,5-trichlorophenoxyacetyl chloride (19.2 g.; 0.070 mol) in benzene (50 ml.), prepared in Example 1, was slowly added to the flask. The reaction was exothermic, and the mixture was thereafter stirred at reflux for 6 hours. The reaction mixture was filtered and the solids washed with benzene, treated with hot water, filtered and dissolved in benzene. This benzene solution was combined with the filtrate from the reaction mixture and the benzene washings, and the resulting solution was dried over magnesium sulfate and filtered. The filtrate therefrom was distilled under reduced pressure to remove benzene to yield a solid residue which was recrystallizedfrom heptane and benzene-heptane mixture, and dried to yield solid N-methoxy 2,4,5-trichlorophenoxyacetamide, melting 158-161 C. and having the following elemental analysis:

Calculated for C H Cl NO N Theoretical, percent 4.92 Found, percent 5.02

l EXAMPLE 4 Preparation of N -eth0xy-2,4,5 -trichlorophenoxyacetamide The product of Example 1 is reacted with ethoxyamine hydrochloride according to the technique of Example 3 to yield N-ethoxy-2,4,5-trichlorophenoxyacetamide.

EXAMPLE 5 Preparation 0 f oc- N-n-p r0 p oxy -N -m ethy l -2 ,4 ,5 trichlorophenoxy -propionamide a-(2,4,5-trichlorophenoxy) -propionic acid, which can be prepared by treating 2,4,5-trichlorophenol with sodium hydroxide and then OC-bIOmOPI'OPlOIllC acid, is treated with thionyl chloride by the procedure of Example 1 to obtain cr-(2,4,5-trichlorophenoxy)-propionyl chloride. This latter intermediate is reacted with N-n-propoxy-N-methylamine-hydrochloride by the technique of Example 2 to yield the desired product a-(N-n-propoxy-N-methyl-2,4,5- trichlorophenoxy)-propionamide.

EXAMPLE 6 Preparation 0 f 'y- (N -meth0xy-2,4,5 -trichl0r0phen0xy n-butyramide 'y-(2,4,5-trichlorophenoxy)-n-butyric acid, which can be prepared by treating 2,4,5-trichlorophenol with sodium hydroxide and then 'y-bromo-n-butyric acid, is treated with thionyl chloride by the procedure of Example l'to obtain -(2,4,5-trichlorophenoxy)-n-butyryl chloride. This intermediate is reacted with methoxyamine-hyrochloride according to the technique of Example 3 to yield the desired product 'y-(N-methoxy2,4,5-trich1orophenoxy) -n-butyramide.

EXAMPLE 7 Preparation of 6- (N -eth0xy-N -ethyl-2,4,5 -trichl0r0- phenoxy -n-valeramide 6-(2,4,5-trichlorophenoxy) -n-valeric acid, which can be prepared by treating 2,4,5-trichlorophenol with sodium hydroxide, and then fi-bromo-n-valeric acid, is treated with thionyl chloride by the method of Example 1 to obtain 6-(2,4,5-trichlorophenoxy)-n-valeryl chloride. This inter mediate is reacted with N-ethoxy-N-ethylamine-hydrochloride according to the procedure of Example 2 to yield the desired product 6-(N-ethoxy-N-ethyl-2,4,S-trichlorophenoxy) -n-valeramide.

Other compounds within the scope of the present invention can be prepared in the manner detailed in the previous examples. Given in Examples 8-16 are the free acid and the amine reactants which can be used to prepare the indicated named compounds of this invention.

EXAMPLE 8 ,6- (2,4,5 -trich1orophenoxy) -n-butyric acid+N-methoxy- N n butylamine=fi-(N-methoxy-N-n-butyl 2,4,5 trichlorophenoxy) -n-butyramide.

EXAMPLE 9 a-(2,4,5-trichlorophenoxy)-iso-butyric acid-l-N-ethoxy- N n propylamine:a-(N-ethoxy-N-n-propyl-2,4,S-trichlorophenoxy) -iso-butyramide.

EXAMPLE 10 ,8- 2,4,5 -trichlorophenoxy) -n-propionic acid+N-methoxy N methylamine=fl-(N-methoxy-N-methyl-2,4,5- trichlorophenoxy) -n-propionamide.

EXAMPLE 11 2,4,S-trichlorophenoxyacetic acid+n-butoxyamine=N- n-butoxy-2,4,S-trichlorophenoxyacetamide.

EXAMPLE 12 'y (2,4,5-trichlorophenoxy)-n-valeric acid-i-methoxy- N methylamine='y-(N-methoxy-N-methyl 2,4,5 trichlorophenoxy)-nvaleramide.

EXAMPLE 14 a-(2,4,5-trichlorophenoxy)-n-butyric acid-l-N-methoxy- N methylamine=u-(N-methoxy-N-methyl 2,4,5 trichlorophenoxy)-n-butyramide.

EXAMPLE 15 fl-(2,4,5-trichlorophenoxy) -iso-propionic acid-l-N-methoxy-N-methylamine= p-(N-methoxy-N-methyl-2,4,5 trichlorophenoxy)-iso-propionamide. EXAMPLE 16 w(2,4,5-trichlorophenoxy)-iso-butyric acid-I-N methoxy N methylamine=w(N-methoxy-N-methyl-2,4,5- trichlorophenoxy) -iso-butyramide.

For practical use as pre-emergence herbicides, the compounds of this invention are generally incorporated into herbicidal compositions which comprise an inert carrier and a herbicidally toxic amount of such a compound. Such herbicidal compositions, which are usually known in the art as formulations, enable the active compound to be applied conveniently to the site of the soil to .be treated in any desired quantity. These compositions 'can be solids such as dusts, granules, or wettable powders; or they can be liquids such as solutions or emulsifiable concentrates.

For example, dusts can be prepared by ginding and blending the active compound with a solid inert carrier such as the talcs', clays, sil'cas, pyrophyllite, and the like. Granular formulations can be prepared by. impregnating the compound, usually dissolved in a suite ble solvent. on to and into granulated carriers such as the attapulgites or the vermiculites, usually of-a particle ize'range of from-about 0.3 to 1.5 mm. Wettable powders, which can be dispersed in water to any desired concentration of the active compound, can be prepared by incorporating wetting agents into concentrated dust compositions.

In some cases-the active compounds are sufficiently soluble in common organicsolvents such as kerosene or xylene so that they: can be used directly as solutions in these solvents. However, preferred liquidherbicidal compositions are emulsifiable concentrates, which comprise an active compound according to this" invention and as the inert carrier, a solvent and an emulsifier. Such emulsifiable concentrates can be diluted with water to any desired concentration of active compound for application as sprays to the site of the soil to be treated. The emulsifiers most commonly used in these concentrates are nonionic or mixtures of nonionic with anionic surface-active agents.

A typical herbicidal composition according to this invention is illustrated by the following example, in which the quantities are in parts by weight.

EXAMPLE 17 Preparation of a dust Product of Example 2 1O Powdered talc 90 The above ingredients are mixed in a mechanical grinder-blender and are ground until a homogeneous, freeflowing dustof the desired particle size is obtained. This dust is suitable for direct application to the site of the weed infestation.

The pre-emergence herbicides of this invention can be applied in any manner recognized by the art. The concentration of the new compounds of this invention in the herbicidal compositions will vary greatly with the type of formulation and the purpose for which it is designed, but generally the herbicidal compositions will comprise from about 0.05 to about 95 percent by weight of the active compounds of this invention. In a preferred embodiment of this invention, the herbicidal compositions will comterfering with the production of cultivated crops or with the welfare of livestock. Many types of weeds are known, including annuals'such as'pigweed, lambs quarters yellow foxtail, crabgrass, wild mustard, French-weed, rye-grass, goose-grass, chickweed, and smartweed; biennials such as wild carrot, great burdock, mullein, round-leaved mallow, blue thistle, bull thistle, hounds-tongue, moth mullein, and purple star thistle; or perennials such as while cockle, perennial rye-grass, quackgrass, Johnson grass, Canada thistle, hedge bindweed, Bermuda grass, sheep sorrel, field chickweed, and winter-cress. Similarly, such weeds can be classified as broad-leaf or grassy weeds. It is economically desirable to control the growth of such weeds without damaging beneficial plants or livestock.

The new compounds of this invention are particularly valuable for weed control because they are toxic to many species and groups of weeds while they are relatively nontoxic to many beneficial plants. The method of this invention for the control of weeds comprises applying to the soil containing weed seeds and seedlings, a hericidal composition comprising an inert carrier and as the essential active ingredient, in a quantity which is herbicidally toxic to said weed seeds and/ or seedlings, a compound of this invention. Application of the herbicidal composition is preferably made to the soil at or before the time of planting or between planting and the emergence of desirable plants. Where the soil is to be treated between planting and emergence of desirable plants, it is preferred to plant the seeds of desirable plants below the zone of the weed seeds. The exact amount of compound required wil depend on a variety of factors including the hardiness of the particular weed species, weather method of applica invention was illustrated, for example, by a number of experiments carried out for the control of various weeds. Many of these experiments were carried out on cra-bgrass. Crabgrass is a term used to describe a group of summer annuals which cause extensive damage to lawns, turf, and other grassy areas, The crabgrass kills by taking moisture and nutrients from the soil and thus smothering and, choking the desirable grasses. The grasses around each crabgrass plant are usually killed or seriously weakened. When the crab grass dies, it leaves bare spots, liberally sprinkled with enough seeds to pro vide serious infestation the next season. The two species of crabgrass which are to the most widespread weed pests of lawns are Digimria ischae'mum, commonly known as smooth crabgrass, and Digitaria sanguinalis, usually known as common, large, airy, ta-l l, purple, fingergrass, turkeyfoot, crowfoot grass, and watergrass. At least fifteen other varieties of Digitaria species of crabgrass are known. Also generally classified with crabgrass are such weeds as goosegrass (Eleusine indica), broomsedge (Andropogon virginicus), pigeon grass or green bristle grass (Setaria viridis), yellow bristle grass (Setaria lutescens), water grass (Echinochloa crusgalli), witchgrass (Punicum capillare), cheatgrass or chess (Bro-mus secalinus), and downy bromegrass (Bromus tectorum).

In one series of tests, seeds of smooth crabgrass (Digitaria ischaemum) and hairy crabgrass (Digitaria sanguinalis) were planted in rows in flats of greenhouse soil. After the seeds were planted and covered with soil, the compounds to be tested were sprayed on the soil as aqueous emulsions at a range of concentrations. The soil was then covered with plasterers grade vermiculite and watered. Growth of the plants were maintained under controlled greenhouse conditions, and plant counts were made approximately 20 days after planting. The results of these tests are summarized in the following table:

Number of Growing Concen- Plants After 20 Days Test Compound tration,

lbs/acre D. D. Ischaemum Sanguinalz's N -Methoxy-1 '-methyl-2.4,5-tricl1l0- ropheroxyacetamide. (Product of Example 2) 2 1 O 1 0 0 1 1 Average s. 1 0

N-Methoxy-n-methyl-2.4.5-trichlorophenoxyaeetamide. (Product 01' Example 2) 4 0 0 0 0 0 0 0 0 Average 0 0 N -Methoxy-n-methyl-2A, 5-trich1o ropher-oxyaeetamide. (Product of Example 2) r. 6 0 0 0 0 0 O 0 0 Average 0 0 Untreated Cheek (Control) .1 40 30 32 31 46 19 47 28 48 25 Average 43 27 I claim: 1. A compound of the formula ([)Z-CN OY H 01 wherein X is selected from the group consisting of hydrogen and alkyl containing from one to ten carbon atoms, Y is alkyl containing from one to ten carbon atoms, and Z is unsubstituted alkylene containing from one to four carbon atoms.

2. A compound of the formula wherein X is selected from the group consisting of hydrogen and unsubstituted alkyl containing from one to ten carbon atoms, Y is unsubstituted alkyl containing from one to ten carbon atoms, and Z is unsubstituted alkylene containing from one to four carbon atoms.

3. N-methoxy-2,4,5-trichlorophenoxyacetamide.

4. N methoxy N methyl 2,4,5 trichlorophenoxyacetamide.

5. N-ethoxy-2,4,5-trichlorophenoxyacetamide.

6. oz (N methoxy N methyl 2,4,5 trichlorophenoxy) -propionamide.

7. a (N methoxy N methyl 2,4,5-trichlorophenoxy -n-butyramide.

8 {3 (N methoxy N methyl 2,4,5 trichlorophe noxy -propionamide.

9. a (N methoxy N methyl 2,4,5 trichlorophenoxy) -iso-butyramide.

References Cited in the file of this patent UNITED STATES PATENTS 2,723,192 Todd Nov. 3, 1955 2,726,150 Wolter Dec. 6, 1955 2,832,767 Boettner Apr. 29, 1958 2,911,440 Thuillier et al. Nov. 3, 1959 2,948,754 Litvan et a1. Aug. 9, 1960 3,027,407 Major et al. Mar. 27, 1962 3,029,277 Metivier Apr. 10, 1962 FOREIGN PATENTS 875,807 Germany May 7, 1953 OTHER REFERENCES Eckstein et a1.: Chemical Abstracts, vol. 52, pages 16, 616-16, 617 (1958). 

1. A COMPOUND OF THE FORMULA 